An electromagnetic circuit breaker is basically a relay that operates to be a switch that is automatically opened when the armature is tripped, as for example when a current or voltage, or the combination of both, exceeds a certain limit. Typically, the automatic operation of such circuit breakers depends on an electromagnetic coil penetrating and a mechanism inside the circuit breaker. Such circuit breakers are also designed to be manually operated, for example with a handle or toggle actuator, but such breakers usually retain the capacity to be automatically tripped even if the handle is forcibly held in the on position so called “trip free” operation).
Such circuit breakers are designed to provide current and voltage through an electromagnetic coil to a load. The electromagnetic coil commonly surrounds a delay tube in which a plunger or core is adapted to be drawn magnetically toward a pole piece at the end of the delay tube by the flux created by the electromagnetic coil. The circuit breaker frame typically supports the coil and also supports a circuit breaker mechanism that is adapted to be tripped by a movable armature. The frame sets up a magnetic circuit with the coil and the armature. The armature when moved by the magnetic circuit engages a sear to open electrical contacts provided in an arc chamber that is also defined in the circuit breaker housing. Thus the breaker is a switch designed to automatically open in response to an over current and/or over voltage condition.
Typical circuit breaker housings are made in two half sections, each of which sections is molded from a plastic dielectric material. The half sections are held together by fasteners. The fastened housing supports the circuit breaker mechanism, frame, armature, and terminal components. The molded half sections are generally provided with slots to receive arc splitter plates that are arranged in spaced relationship along the path of movement for a movable contact as it travels from a closed position, in engagement with the fixed contact provided on one of the terminal studs in the circuit breaker housing, to an open position, where the movable contact is spaced from the fixed contact. The movable contact is generally provided on the underside of a movable contact arm that provides an electrical path through the movable contact to the fixed contact in the closed condition of the circuit breaker.
When circuit breakers are used in conjunction with sensitive DC electronic circuits, reverse polarity protection is important. Electronic circuits and devices to which magnetic circuit breakers are commonly connected are inherently polarity sensitive. Often, the breaker terminals are identical and reverse installation occurs.
Even with the protection afforded by present day breaker assemblies, the installer can fail to recognize the reverse connection and continually try to reset the breaker. Thus, the prior art designs permit continual resetting until the voltage polarity is corrected. Several reset cycles, however, may cause polarity sensitive circuit devices to be destroyed during such ill advised routing of a breaker assembly.
The present invention provides a redesigned voltage coil and polarity detection circuit. When a circuit breaker assembly is wired incorrectly with reversed polarity, the voltage coil of the present invention will trip another breaker mechanically connected thereto. The voltage coil is designed for continuous operation and remains energized as long as the voltage polarity is in the reverse direction. Further, the voltage breaker of the present invention is advantageously designed so that as long as a reverse polarity condition exists, the armature in the voltage breaker will be maintained in an OFF position (i.e., the armature is magnetically in contact with the pole), automatically the circuit breaker assembly from being rest. Thus, an installer would be unable to reset the circuit breaker assembly to the ON position or cause the contacts to re-engage. Further, the breaker will remain tripped even if the installer holds the switch in an ON position. Accordingly, momentary power and associated current inrushes commonly experienced with the prior art DC reverse polarity breakers are eliminated. Power may only be restored to the circuit which is being protected if the polarity is corrected.
The unique circuitry of the present invention does not disturb normal operation of the breaker in the event that polarization is correct. Only in the event of a reverse polarity set-up will the reverse polarity circuitry have any effect.